Carleton University

About: Carleton University is a education organization based out in Ottawa, Ontario, Canada. It is known for research contribution in the topics: Population & Large Hadron Collider. The organization has 15852 authors who have published 39650 publications receiving 1106610 citations.

Theoretical Calculation of Substituent Effects on the O−H Bond Strength of Phenolic Antioxidants Related to Vitamin E

Abstract: Calculations on phenol and a large number of phenols substituted with methyl, methoxyl, and amino groups have yielded reliable gas-phase O−H bond dissociation energies, BDE(ArO−H)gas. Geometries for the phenol, ArOH, and aryloxyl radical, ArO, were optimized at the (semiempirical) AM1 level followed by single point density functional theory (DFT) calculations using a 6-31G basis set supplemented with p-functions on the hydrogen atom and the B3LYP density functional. This gave BDE(PhO−H)gas = 86.46 kcal/mol, which is in good agreement with the experimental value of 87.3 ± 1.5 kcal/mol. All but one of the compounds and conformations examined had weaker O−H BDE's than phenol, the exception being o-methoxyphenol with the O−H group pointing toward this substituent (BDE = 87.8 kcal/mol). Where comparison was possible, calculated differences in O−H BDE's were in excellent agreement with experiment (better than 1 kcal/mol). A simple group additivity scheme also gave excellent agreement with calculated BDE (ArO−H)...

Interindividual use of echolocation calls: Eavesdropping by bats

Abstract: The use of other individual's echolocation calls by little brown bats, Myotis lucifugus, was tested by observing the response of free-flying bats to presentations of recorded echolocation calls and artificial sounds. Bats responded by approaching conspecific calls while searching for food, night roosts, nursery colonies and mating/hibernation sites. Response was low or non-existant to other sounds. While searching for prey, M. lucifugus also responded to the echolocation calls of Eptesicus fuscus, a sympatric species with overlapping diet but distinctly different echolocation calls. Subadults were especially responsive to conspecific calls. All four situations in which the bats responded involve patchily distributed resources at which bats accumulate. Concentrations of echolocation calls thus likely serve as cues regarding the location of resources. Individuals approaching feeding groups, for example, could increase prey detection range by up to 50 times over individuals relying solely on their own echolocation. Although the costs associated with eavesdropping may be negligible for M. lucifugus, for other species, particularly territorial ones, being conspicuous may be a disadvantage and the possibility of being over-heard by other bats may have been one factor involved in the evolution of echolocation call design.

An Integrative Model of Place Image: Exploring Relationships between Destination, Product, and Country Images

Abstract: To advance place image theory, this study combines elements from two areas that have explored place image more than any others: tourism destination image (TDI) and product-country image (PCI). Key constructs from each are measured simultaneously in an Integrative Model of Place Image. The model test uses consumer survey data from South Korea to compare image measures of the United States and Japan using structural equation modeling. The results reveal that cognitive country image has greater influence on product factors than on destination factors, while affective country image has greater influence directly on receptivity than indirectly on beliefs. In addition, consumer beliefs exhibit a strong crossover effect between product beliefs and destination receptivity. Newly tested relationships point to a number of directions for future research in place image and branding, and provide empirical evidence of the need for place marketers to move toward greater integration between product- and tourism-oriented ...

Cytokines, stress, and depressive illness.

Abstract: It has been suggested that immune activation, and particularly increased activity of several cytokines, notably interleukin-1, interleukin-2, interleukin-6, tumor necrosis factor-alpha as well as their soluble receptors is characteristic of depression. Normalization of cytokine activity does not necessarily occur following successful antidepressant, suggesting that cytokines may be trait markers of depression, or simply represent bystander effects of the illness. The relationship between cytokines and depression is complicated as a variety factors could directly or indirectly influence cytokine activity. While cytokine elevations are most pronounced in severe (melancholic) depression, their activity may also be related to chronicity of illness, neurovegetative features of depression (altered sleep patterns, food intake, weight changes, fatigue or general activity), or the high stress perception characteristic of depression. Although, studies assessing cytokines in depressive populations are basically correlational in nature, patients receiving cytokine immunotherapy frequently show depressive symptoms, which may be attenuated by antidepressant medication, supporting a causal role for cytokines in depressive disorders. The processes underlying such outcomes remain to be established, but the affective changes may stem from the neuroendocrine and central neurochemical changes elicited by cytokines, as these are reminiscent of those associated thought to subserve depression.